Power transmission



April 25, 1950 M. A. HAYDEN 2,505,710

' POWER TRANSMISSION Filed March 30, 1946 M 4 Tua/A Patented Apr. 25, 1950 UNITED STATES PATENT OFFICE Vickers Incorporated,

ration of Michigan Detroit, Mich., a corpo- Application March 30, 1946, Serial No. 658,517

9 Claims. (Cl. 60m-52) This invention relates to power transmissions, particularly to those of the type. comprising two or more fluid pressure energy translating devices, one of which may function as a pump and another as a fluid motor.

The invention is more particularly concerned with a directional control valve for use in a hydraulic transmission containing a reversible fluid motor for causing an automatic and continuous reciprocation oi said motor. In the past it has been the practice to incorporate in such a transmission a mechanically operated pilot valve and a fluid operated reversing valve, the pilot valve being mechanically actuated by the motor at each end of the motor stroke so as to cause reverse actuation of the reversing valve and the latter finally reversing the direction of flow to and from the motor.

Where a time delay between the end of one stroke of the motor andthe beginning of another stroke Was to be avoided, some means was provided to speedily actuate the reversing valve so as to immediately start the reverse movement of the motor.

It is an object of this invention to provide a control valve for use in a hydraulic transmission containing a reversible fluid motor which will automatically cause a continuous reciprocatingr movement of said motor.

It is a further object of this invention to provide a control valve for use in a transmission and for the purpose as above stated which will cause a reversal of the motor stroke at each end thereof with a minimum of time delay.

It is also an object of this invention to provide a valve of this character for the purpose as above stated which will cause reversal of motor stroke with a minimum of time delay by reason of being initially mechanically actuated by the motor before change over of porting connections of the valve takes place and subsequently actuated completely and speedily by pressure fluid as said change over of porting connections is taking place.

It is a further object of this invention to provide a valve of this character for the purpose as above stated which obviates the necessity of using a separate pilot valve mechanically actuated at each end of the motor stroke together with a fluid actuated reversing valve, because of having inherent operational characteristics insuring complete actuation to reverse the direction of movement of the motor.

It is a further object of this invention to provide a directional control valve to obviate the necessity ot using both a pilot valve and a reversing valve by reason of being actuated initially by mechanical means and insuring complete actuation by hydraulic means.

It is also an object of this invention to provide a valve of this character and for the above purposes which will be simply and economically manufactured and which will give a long and useful life.

Further cbiects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred form oi' the present invention is clearly shown.

In the drawing:

Figure l is a diagrammatic view of a hydraulic transmission incorporating a cross sectional view of a preferred form of the present invention.

Figure 2 is a perspective view of a preferred form of the present invention.

Referring now to Figure l, there is shown a pump I 0 which is driven by an electric motor l2 and which has a suction conduit i 4 connected to a tank I6 and a fluid delivery conduit I3 connected to the pressure port 2u of. a directional control valve 22. Valve 22 is also provided with externally located discharge ports 24 and 26 and a tank port 28. Tank port 28 is connected to tank I6 by means of a conduit 30 while the discharge ports 24 and 26 are connected by conduits 34 and 36 to the head and rod ends, respectively, of a reversible motor 32 `comprising a cylinder 3B containing a piston 40 connected to which is a piston rod 42.

Incorporated in the pump delivery conduit i8 is a relief valve 44 of suitable construction which will exhaust excessive pressure fluid to tank I8 by means of an exhaust conduit 45 whenever a predetermined pressure within the system is created as determined by the setting of valve 44. Valve 22 is comprised of a body 45 having a 1ongitudinal bore 46 extending completely across the body which is intersected midway thereof by a pressure passage 48 constructed from the bottom of body 45 and by duplicate vertical exhaust passages 50 and 52 constructed from the top of body 45 and intersecting bore 46 at a point equi-distant from pressure passage 48. A longitudinal passage 54 connects passage 52 to passage 50 and the terminus of passages 52 and 54 are closed by plugs 56.

Reciprocably mounted within bore 46 is a valve spool 58 having spaced apart centrally located lands and 62 forming a reduced portion 64 therebetween and larger left and right end lands 66 and 68, respectively, forming a reduced portion 18 between left end land 66 and center land 68 and a reduced portion 12 between right end land 68 and center land 62. A duplicate plurality of transverse passages 14 and 'i6 are located, respectively, in reduced portions 18 and 12. Transverse passages 14 intersect a longitudinal passage 18 extending completely through left end land 66 while transverse passages i6 intersect a duplicate longitudinal passage 88 extending completely through right end land 68.

Transverse passages 14 and 'i6 are adapted to be alternately in communication with pressure passage 48 so as to direct iluid from pump i8 to the discharge ports 24 and 25 and alternately in comn munication with exhaust passages 58 and 52 so as to direct exhaust fluid from motor 32 to tank port 28. Alternately, while one plurality of transverse passages is in communication with the pressure passage 48 and blocked from communication from f one of the exhaust passages, the other plurality of transverse passages will be blocked from communication with the pressure passage 48 and open to communication with the other exhaust passage.

Spool 58 is limited in rightward or leitward movement by duplicate discharge port connections 82 which form the externally located discharge ports 24 and 26. Spool 58 is adapted to be initially actuated in either direction to a point just past the center position by mechanical means and for this purpose pressure passage 48 is constructed large enough for mounting a lever arm 84 which is bifurcated at the upper end as indi-1 cated by the numeral 85 so as to t around the reduced portion'64 of Spool 58. A shaft 86 which extends from body 45 shown more clearly in Figure 2 is rotatably mounted in a transverse bore of body 45, not shown, which intersects passage 48 and is tightly inserted within a bore 88 of lever arm 84, shaft 86 being connected to arm 84 by means-of a set screw 88. Thus, with rabbit ears 92 attached to the extended portion of shaft 86 shown in Figure 2 being contacted at each end of the motor stroke by means of dogs 84 attached to motor 32, as shown in Figure l, in the well known manner, so as to rotate shaft 86, lever arm 84 is rotated to shift the spool 58. Areas at the left and right ends of spool 58 indicated by the numerals 96 and 98 are subject to pressure fluid for hydraulically completing the shifting of spool 58.

In operation. as shown in Figure l, with lever arm 86 rotated completely to the left, transverse passages 16 are opened to the pressure passage 48 and transverse passages 14 are opened to exhaust passage 58. Pressure uid delivered by pump I8 to delivery conduit I8 enters pressure port 28 of control valve 22 and by means of pressure passage 48 and transverse port 16 enters the longitudinal passage 88 of piston 58 from where it may flow through discharge port 26 to the rod end of motor 32 by means of conduit 36. Exhaust fluid from the head end of motor 32 is delivered to discharge of valve 2E by means of conduit 34 from which it may flow to tank I6 by means of passage 18 in piston 66, transverse ports 14 in reduced portion 18, exhaust passage 50, exhaust port 28 and exhaust conduit 38.

When piston 48 of motor has shifted to the right sufficient enough for one of the dogs 94 connected to the motor to contact one of the rabbit ears 82 connected to the shaft 86, shaft 88 will be rotated in the clockwise direction to rotate lever am 84 thereby shifting spool 58 rightwardly. spool 58 reaches the dead center position transverse ports 18 are blocked from communication with pressure passage 48 and exhaust passage 62 and transverse ports 14 are blocked from communication with pressure passage 48 and exhaust passage 58.

A slight overtravel of the piston 48 is sufficient to shift spool 58 just past the dead center position at which. point transverse ports 16 come into contact or communication with exhaust passage 52 and transverse ports 14 are just coming into communication with pressure passage 48.

Pressure fluid from pump I8 is now free to enter port 28 and flow to the head end of motor 32 by means of transverse ports 14, passage 18 in piston 66, discharge port 24 and conduit 34. However, the area 96 at the extreme end of piston 66 is exposed to this flow of fluid from pump I8 and as the fluid volume and force needed to shift valve 58 is much less than that required to shift piston 48 of motor 32, spool 58 will rapidly complete shifting rightwardly by means of this pressure fluid delivered by pump l0. Upon rapid rightward completion of movement of spool 58 the full volume capacity of pump i8 is free to iiow by means of conduit 34 to the head end of motor 32 to shift piston 48 leftwardly.

When piston 48 has shifted leftwardly a sumcient distance, one of the dogs 94 will contact the rabbit ears 82 rotating lever 86 in a counterclockwise direction so as to rotate lever arm 806 and shift spool 58 leftwardly. All ports will be blocked at the dead center position of spool 58 but a slight overtravel of the motor is sufficient to shift spool 58 leftwardly just past the dead center position. Transverse ports 16 are now open to pressure passage 48 and pressure fluid from pump i8 is free to act upon the exposed area 98 of land 68 rapidly completing the shifting of spool 58 to the left. Upon complete shifting of spool 86 to the left, as shown in Figure 1 the direction of fluid flow to and from the motor is as before described.

It should be noted that spool 58 is so designed i that at the exact dead center position in bore 46 munication with pressure passage 48 and the other transverse passages with one of the exhaust passages.

It is well known in the art that the inertia of the motor is suicient to overcome the complete blocking of pressure fluid to and from the motor and a very slight overtravel of the motor is sufficient to shift the spool 58 past dead center position. Once past the dead center position during a spool shifting operation the transverse ports 14 and 16 are just beginning to change their connections between the pressure passage 48 and the exhaust passages 58 and 52.

At this point it is desired to rapidly shift the spool 58 so as to rapidly and completely change these connections. Provision has been made for rapid snap action completion of shifting of spool 58 by pressure fluid means in the following manner. Upon shifting of spool 58 just past the dead center position one or the other of transverse ports 14 or 16 will be in communication with pressure passage 48. Thus, pressure fluid is not only free to flow to motor 32 by means of passages 18 or 88, discharge ports 24 or 26, and conduits 34 or 36 but is also free to act upon acuario the exposed area at either extreme end of land 66 or 68 surrounuding the passages 18 and 80 and indicated by the numerals 96 and 90. As the force and volume of iiuid` needed to shift spool B is slight in comparison to that needed to actuate motor 32, the spool 58 will necessarily shift before the piston 40 of motor 32 and will shift speedily because of this exposure of areas 96 or 98 to iluid flow from pump I0.

It should be noted that the body is so designed so as to avoid a multiplicity and complexity of bores.

It should also be noted that fluid is delivered from the pressure passage to the discharge ports completely through the spool by means of passages formed therein and is also directed from the discharge ports to the exhaust ports by means of these very same passages.

It should further be noted that in the past it has been customary to employ a pilot valve and a uid operated reversing valve in conjunction therewith for causing automatic and continuous reciprocating movement of reversible iiuid motor. In this practice the pilot valve is completely actuated mechanically and the reversing valve completely actuated by pressure fluid in order to insure complete operation of the reversing valve. The invention herein described completely obviates the necessity of having both a pilot valve and reversing valve in such a hydraulic transmission because of possessing inherent operational characteristics, that snap completion of actuation by pressure fluid means, which insures full actuation thereof and consequently continuous operation of the fluid operated motor.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

l. A directional control valve of the reversing valve type for use in a hydraulic power transmission system comprising a body having externally located connection ports including a pressure port, a return port and a pair of work circuit ports, a longtitudinal bore connecting the work circuit ports, a -pair of return passages connected to the bore in spaced apart relationship and to the return port and a pressure passage connected to the pressure port and to the bore intermediate the return passages, a valve reciprocably mounted in the bore having a pair of spaced apart radial passages and a passage extending from each end of the valve to its associated adjoining radial passage, means for alternately, initially mechanically shifting the valve to connect one of the radial passages with the pressure passage and the other radial passage with one of the return passages and means for hydraulically completing the shifting of the valve in each direction after a predetermined range of mechanical movement of the valve.

2. A directional control valve of the reversing valve type for use in a hydraulic power transmission system comprising a body having externally located connection ports including a pressure port, a return port and a pair of work circuit ports a longitudinal bore connecting the work circuit ports, a pair of return passages connected to the bore in spaced apart relationship and to the return port and a pressure passage connected to the pressure port and to the bore intermediate the return passages. a valve reciprocably mounted in the bore having a pair of spaced apart radial passages and a passage extending from each end o the valve to its associated adjoining radial passage, means for alternately, initially mechanically shifting the valve to connect one of the radial passages with the pressure passage and the other radial passage with one of the return passages and means for hydraulically completing the shifting of the valve in each direction at the pointone of the radial passages is connected to the pressure passage.

3. Ar directional control valve of the reversing valve type for use in a hydraulic power transmission system comprising a body having externally located connection ports including a pressure port, a return port and a pair of work circuit ports, a longitudinal bore connecting the work circuit ports, a pair of return passages connected to the bore in spaced apart relationship and to the return port and a pressure passage connected to the pressure port and to the bore intermediate the return passages, a valve reciprocably mounted in the bore having its ends exposed to iiuid pressure in the work circuit ports, said spool having a pair of spaced apart radial passages and a passage extending from each end of the valve to its associated adjoining radial passage and means for alternately, initially mechanically shifting the valve to connect one of the radial passages with the pressure passage and the other radial Ipassage with one of the return passages whereby pressure fluid admitted to one work circuit port is effective to shift the spoo] through the remainder of its travel.

4. A directional control valve of the reversing valve type for use in a hydraulic power transmission system comprising a body having externally located connection ports including a pressure port, a return port and a pair of work circuit ports, a longitudinal bore connecting the work circuit ports, a pair of return passages connected to the bore in spaced apart relationship and to the return port and a pressure passage connected to the pressure port and to the bore intermediate the return passages, a valve reciprocably mounted in the bore having its ends exposed to fluid pressure in the work circuit ports, said spool having a pair of spaced apart radial passages and a passage extending from each end of the valve to its associated adjoining radial passage and means extending into the pressure passage and balanced as to the pressure forces acting on it for alternately, initially mechanically shifting the valve to connect one of the radial passages with the pressure passage and the other radial passage with one of the return passages whereby pressure fluid admitted to one work circuit port is effective tc shift the spool through the remainder of its travel.

5. A directional control valve of the reversing valve type for use in a hydraulic power transmission system comprising a body having a main valve bore provided with a central pressure port, a pair of work circuit ports at its opposite ends and a pair of return ports intermediate said ports, a spool shiftable to control communication between said ports and having its ends exposed to fluid pressure in the work circuit ports, the spool having an internal passage at each end opening radially to alternately connect one of the work circuit ports to the pressure port and the other to the adjacent return port and means for shifting said spool from one extreme position to a point just past its central position whereby pressure built up in one work circuit Dort 1s effective to shift the spool through the remainder of its travel.

6. A directional control valve of the reversing valve type for use in a hydraulic power transmission system comprising a body having a main valve bore provided with a central pressure port, a pair of work circuit ports at its opposite ends and a pair of return ports intermediate said ports, a spool shiftable to control communication between said ports and having its ends exposed to fluid pressure in the work circuit ports, the spool having an internal passage at each end opening radially to alternately connect one of the work circuit ports to the pressure pori; and the other to the adjacent return port, and means extending into the pressure port and balanced as to the pressure forces acting on it for shifting said spool from one extreme position to a point just past its central position whereby pressure built up in one work circuit port is effective to shift the spool through the remainder of its travel.

7. A directional control valve of the reversing valve type for use in a hydraulic power transmission system comprising a body having a main valve bore provided with a central pressure port, a pair of work circuit ports at its opposite ends and a' pair of return ports intermediate said ports, a spool shiftable to control communication between said ports and having its ends exposed to iluid pressure in the work circuit ports, the spool having a pair of spaced apart radial passages each of which is adapted to be alternately connected to the pressure port while the other is connected to one of the return ports and an internal passage extending from each end of the spool to its associated adjacent radial pas..

Sage.

-8. A directional control valve of the reversing valve type for use in a hydraulic power transmission system comprising a body having a main valve bore provided with a central pressure port, a pair of work circuit ports at its opposite ends and a pair of return ports intermediate said ports, a spool shiftable to control communication between said ports and having its ends exposed to fluid pressure in the work circuit ports, the spool having a pair of spaced apart radial passages each of which is adapted to oe alternately connected to the pressure port while the other is connected to one of the return ports and an internal passage extending from each end of the spool to its associated adjacent radial passage to connect each work circuit port either to the pressure port or to the adjacent return port and means for shifting said spool from one extreme position to a point just past its central position connecting one of the radial passages with the pressure port whereby pressure fluid admitted to one work circuit port is eiective to shift the spool through the remainder of its stroke.

9. A directional control valve of the reversing valve type for use in a hydraulic power transmission system comprising a body having externally located fluid inlet and discharge connection ports including a pressure port, a return port and a pair of work circuit ports, a longitudinal bore connecting the work circuit ports, said bore also being provided with spaced apart return and pressure ports connected to their corresponding external ports, a valve spool shiftably mounted in the 'core to control communication between said ports having its ends exposed to fluid pressure in the Work circuit ports and being provided with an internal passage at each end opening radially to alternately simultaneously connect a valve bore return port to one of the work circuit ports and the valve bore pressure port to the other work circuit port and means for shifting said spool from one extreme position to a point just changing said porting connections whereby the valve bore pressure port is simultaneously connected to one of the work circuit ports and to one end of the spool for permitting pressure uid in said work circuit port to shift the spool through the remainder of its stroke.

MERRILL A. HAYDEN.

REFERENCES CITED The following references are of record in thev file of this patent:

UNITED STATES PATENTS 

